This invention relates generally to porous fiber reinforced thermoplastic polymer sheets, and more particularly to porous fiber reinforced thermoplastic polymer sheets that include an integral hinge area.
Porous fiber reinforced thermoplastic sheets have been described in U.S. Pat. Nos. 4,978,489 and 4,670,331 and are used in numerous and varied applications in the product manufacturing industry because of the ease of molding the fiber reinforced thermoplastic sheets into articles. Known techniques, for example, thermo-stamping, compression molding, vacuum forming, and thermoforming have been used to successfully form articles from fiber reinforced thermoplastic sheets.
Some articles require portions of the fiber reinforced thermoplastic sheets to be subjected to sharp bends during the stamping or molding process. Also some articles, such as automotive instrument panels with integral airbag doors require a hinge to permit the airbag door to open during deployment of the airbag. Known techniques for providing a hinge function in a thermoplastic sheet includes steel inserts, plastic clips and glued-on plastic support skins. These known techniques increases article costs, fabrication equipment costs, and manufacturing complexity.